It’s a Girl! Is sex selection the first step to designer children?
By Kathleen Fackelmann Science News Online
Contributed by Jodie Miller
November 28, 1998
Some parents-to-be hope for a girl. Some wish for a boy. The outcome,
however, has always been pretty much a matter of chance.
Researchers at the Genetics & IVF Institute in Fairfax, Va., recently
announced a technique that helps stack the odds in favor of parents
getting what they want. Using a mechanical sperm sorter, the Fairfax team
reported that nearly 93 percent of the babies born were of the desired
sex.
All the couples in this study wanted girls. However, the technique also
can easily help those who desire a boy. Will such technology lead to a
United States overpopulated by one sex? Most ethicists don’t think that
will happen any time soon. Nonetheless, the new technology raises some
concerns about the future, they say.
Before getting to the ethical debate about sex selection, consider the
research itself. Reproductive biologist Edward F. Fugger and his
colleagues at the Genetics & IVF Institute began their study by recruiting
119 couples who wanted a baby girl. In most cases, the couples already had
a boy or boys, and they wanted a girl for variety—to balance their family,
as the scientists say. In a few cases, couples faced the risk of giving
birth to a child with a genetic disorder that strikes boys only.
The patented sperm sorter used by Fugger and his team helps parents pick
out the child’s gender before fertilization of the egg. The technology,
developed during animal studies by Lawrence A. Johnson of the U.S.
Department of Agriculture in Beltsville, Md., exploits the difference in
amounts of DNA in X and Y chromosomes. Sperm bearing the X, or female,
chromosome have more DNA than sperm carrying the Y, or male, chromosome.
An embryo resulting from the merger of an egg, which always carries an X
chromosome, and a sperm carrying an X chromosome will have two Xs and,
therefore, develop into a girl. An egg fertilized by a sperm carrying a Y
chromosome becomes a boy.
In the September issue of Human Reproduction, Fugger and his colleagues
describe their use of the method. Each couple provided a sperm sample,
which the researchers treated with a dye that attaches to DNA and glows
under laser light. The team then exposed the tagged sperm to a laser beam.
The researchers reasoned that the X-carrying sperm would glow the
brightest under the laser light. Sure enough, even though sperm carrying
an X chromosome—and 22 other chromosomes—contain only 2.8 percent more DNA
than those bearing a Y, the sorter separated the bright sperm from the dim
sperm. It then directed most of those bearing X chromosomes to swim down
one collection tube, and most of the Y-bearing sperm went down another
tube.
When the researchers analyzed the sperm in the X collection tube, they
found that 85 percent had the X chromosome, as desired. The researchers
thus estimate that samples from the X collection tubes are five to six
times as likely to result in a girl baby than in a boy.
In 92 cases, the researchers inserted the sorted sperm directly into the
woman’s uterus, a procedure called intrauterine insemination. In this
version of artificial insemination, the sperm must latch onto and
fertilize an egg in the woman’s body for pregnancy to occur.
Some of the couples required more complex—and expensive—techniques to
achieve pregnancy. In 27 cases, the researchers united sperm and egg in a
laboratory dish and then transferred the resulting embryos to the woman’s
uterus.
Out of 119 women, 29 got pregnant using the sorted sperm. In 8 women, the
pregnancy ended in miscarriage or surgery, the latter because of a
dangerous condition in which the fertilized egg starts to grow in a
fallopian tube above the uterus. At the time the Fairfax researchers
published their journal article, 12 women had ongoing pregnancies and 9
women had already delivered 11 babies, including two sets of twins. As of
mid-November, Fugger and his colleagues had not released updated results.
Of the 14 pregnancies in which the gender of the child had been
determined, 13 were girls, the researchers say.
Fugger and his team are also conducting a study with parents who want
boys. In such cases, the sperm sorter is less effective at concentrating
Y-bearing sperm. Still, the method yields a sperm sample in which 65
percent carry the Y chromosome, Fugger says. The team has not announced
any results of that study yet.
The researchers identified no safety concerns in the published study. "All
of the babies born have been healthy," Fugger says. "That doesn’t mean
that all of the risk has been excluded," he says. "There’s a lot that’s
not known."
The study raised more concerns than just the usual fear about side
effects. For some people, a technology that could pick out the sex of a
baby raises the specter of China’s overabundance of baby boys.
Many Chinese couples opt for an abortion of a female fetus if they lose
the natural-reproduction lottery by not conceiving a boy, notes ethicist
R. Alta Charo of the University of Wisconsin-Madison. As a result, China
has experienced some significant demographic shifts, Charo notes.
Most people in the United States recoil at the thought of a society so
geared toward male offspring that abortion—and even infanticide—is the
fate of some baby girls. Indeed, Arthur Caplan of the University of
Pennsylvania’s Center for Bioethics says most U.S. couples have only a
moderate preference for a child of a given sex. If they lose the
reproduction lottery for the gender they desire, they rarely opt for an
abortion, he says.
Furthermore, Caplan says that only a small subset of the U.S. population
would try to ensure their baby’s gender with this expensive, difficult
technique. Charo agrees, noting that a man must first produce a sperm
sample for the doctor. Then, his partner must submit to artificial
insemination or other techniques performed in a doctor’s office or clinic.
Of course, Charo notes, for couples who can have children no other way,
the difficulties of such high-tech reproductive methods are a small price
to pay for a successful pregnancy. But for couples whose only concern is
the gender of their baby, the rigmarole might very well put them off.
Caplan argues that sex selection to balance a family is ethically
acceptable but that it won’t be popular enough in the United States to
change Mother Nature’s gender sorting.
He wonders whether the preference for a boy or a girl stems from
inherently sexist attitudes. Does a U.S. parent’s desire for a boy or a
girl mean that one sex is viewed as inferior to the other? "Sex selection
doesn’t bother us - sexism does," Caplan says.
Sex ratios and sexism aside, some ethicists worry about a culture where
parents are driven to pick out any of the traits of their unborn children.
"There’s a notion now that parenting is a kind of consumer experience,"
says Barbara Katz Rothman, a sociologist at the City University of New
York.
Rothman, for example, worries about parents who choose a sex because they
are seeking to fill stereotypical, perhaps unrealistic roles. For example,
a woman who hopes for a girl may say she wants to shop for a prom gown or
go for manicures with a daughter. "You listen to this woman and think,
‘This woman is not prepared for a 300-pound, 6-foot girl who wears denim
and boots,’" Rothman says.
The trend toward more parental control over a child’s characteristics will
increase in the future, warns biomedical ethicist Thomas H. Murray, the
director of the Center for Biomedical Ethics at Case Western Reserve
University in Cleveland. Murray notes that scientists working on the human
genome project soon will have methods of identifying disease-causing genes
as well as the DNA that produces characteristics such as hair color,
height, athletic ability, and perhaps some behaviors.
Most ethicists see no problem with parents trying to avoid a genetic
disease in their offspring, but Murray and others say that parents should
leave the selection of nondisease traits to fate.
"As consumers, we think, ‘The more choice the better,’" he says. But even
rudimentary attempts to pick one trait from column A and one from column B
might encourage the belief that parents can design the perfect baby,
Murray says. Substantially increased parental control over their tyke’s
personality may change the dynamics of the parent-child relationship, he
adds.
Charo says that selecting a child’s sex is a far cry from designing a
baby. Indeed, while parents can now pay for sorting X- and Y-carrying
sperm, the technology hasn’t been invented that could guarantee a
red-haired cellist with a genius-level IQ.
She adds that sex-selection techniques may be useful to limit the size of
all- girl families where the parents might otherwise continue having
babies until they get a son or of all-boy families intent on having a
girl. "This technology would let couples up the odds that their next kid
will be the last kid," Charo says.
Caplan and Charo both propose that regulation of the technology is not
necessary. "The presumption in the United States is that you let people do
what they want unless there is a very good reason to stop them," Charo
says. "In the United States today, the harm [of sex selection] is not that
great."
Although lawmakers may never regulate sex-selection methods, Murray
contends that genetic counselors should begin developing guidelines to
steer couples away from the designer-baby concept. The harm to society
from attempts to select human characteristics may be subtle, he says. For
example, how will parents who think that they have designed a child act
toward that offspring when a wrong trait shows up?
Rothman says that even with all the human reproductive genetic advances,
one thing should remain the same: "When you parent, you get what you get."
From Science News, Vol. 154, No. 22, November 28, 1998, p. 350. Copyright
1998 by Science Service.
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References:
Fugger, E.F., et al. 1998. Births of normal daughters after MicroSort
sperm separation and intrauterine insemination, in vitro fertilization, or
intracytoplasmic sperm injection. Human Reproduction (September).
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